My armature isn't moving my mesh
This missing piece to your model is the process of weight painting, which I started here:



Your model -- at least the one you uploaded for me to look at -- does not have weighting that assigns each bone to the mesh: The bluer the mesh is for a particular bone, the LESS it is attached/attracted by the bone. The redder the mesh is, the MORE it follows the bone.

The subject of weight painting is one that is covered here and in other online tuts very well... but the summary answer to your question is "because your model is not weight painted...."

Some resources here: https://blender.stackexchange.com/search?q=weight+painting

and here might be another place to start:
https://www.youtube.com/watch?v=S0VS0IVylzg

Please let me know if I missed the point of your question, though... I often do!

best
rg